This strategy differs from the other LTE carriers in the U.S.: virtual network operators buying wholesale airwaves from AT&T and Verizon typically don’t get access to the much faster LTE services. Sign up with any of the TracFone brands, for example, and you’ll only get to use 3G for your mobile web. Keeping LTE for contract customers only ensures a higher, longer-term revenue stream for AT&T and Verizon.

So why would Sprint diverge from the pack of contract carriers and offer LTE to its prepaid brand? Two reasons.

First, it can provide a small boost — no pun intended — to overall revenues by standing out from the prepaid crowd with LTE as an option. If few or no other prepaid brands offer LTE, Sprint stands to gain prepaid customers who value faster mobile broadband over voice minutes and text messages.

Second, and perhaps more important, Sprint quietly adds a second tier of service for its LTE customers. While Boost Mobile advertises unlimited web, the fair-use terms are actually a soft cap of 2.5 GB per month. That plan is $55 a month. Sprint customers that want truly unlimited LTE access can do so on the same network through Sprint directly, for $80 a month with a limited amount of voice minutes; unlimited everything adds another $30 per month.

The new LTE phones for Boost Mobile then, provide Sprint two ways to deliver LTE to its customers, regardless of whether they’re fine with contracts or prefer a month-to-month option. That could sway some to Sprint, which in turn starts recouping its LTE network investments a little faster.